1. Field of the Disclosure
The present disclosure relates to a heater for a fixing device. The heater is for heating and fixing an image onto a recording material.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 06-250539 discloses a heating apparatus in which a heater heats an object to be heated (hereinafter may simply be referred to as “object”) through a heat-resistant film. The heater includes an electric heating body and a plurality of electrodes that supply power to the electric heating body. The electrodes are arranged on the electric heating body in a direction orthogonal to the direction of travel of the object such that different polarities alternate. This configuration can reduce the power supply and current carrying distance. Therefore, even when a material with a high volume resistivity is used, a sufficient amount of heat can be generated and heating can be performed as desired.
In the heating apparatus described in Japanese Unexamined Patent Application Publication No. 06-250539, the electrodes of different polarities are alternately arranged in a comb-like shape. Heating body elements are each formed by a segment of the electric heating body, the segment being interposed between two adjacent electrodes. Each heating body element in an interelectrode region has a high temperature because of heat generated by current flowing from one to the other of the adjacent electrodes. On the other hand, at positions corresponding to the respective electrodes, an increase in the temperature of the electric heating body is smaller than that in the interelectrode regions. This means that in the electric heating body, there is a temperature difference between the interelectrode regions and the positions corresponding to the electrodes. Since the electrodes are arranged in the direction orthogonal to the direction of travel of the object, the electric heating body has streaks of low-temperature portions at the positions corresponding to the electrodes, along the direction of travel of the object. This leads to an uneven distribution of heat applied to the object.